Metal‐Catalyzed Annulations via Activation of Alkenyl CH Bonds

Abstract Annulations initiated by CH activation processes have emerged as powerful tools for the synthesis of cyclic compounds from acyclic precursors, in a straightforward, direct, and atom efficient way. Traditionally, most of these annulations involve the activation of C(sp 2 )H bonds in aromatic compounds; but, more recently, this chemistry is also being extended to alkenes, which is highly attractive, but also challenging, because it requires to avoid side reactivity pathways typical of double bonds. In this article, we revise the more relevant advances in the field together with an explanation of key mechanistic features of each type of reaction.